Deal suspended

The agreement was part of a deal for the United States to supply 240,000 tonnes of food aid to North Korea.

It also agreed to allow UN inspectors in, the US said.

That deal has now been suspended.

The overture from Pyongyang came three months after Kim Jong-un came to power in North Korea, following the death of his father, Kim Jong-il.

North Korea last carried out a rocket launch three years ago, in April 2009, which it characterised as a test of satellite technology. It said the rocket made it into orbit, though the US and Japan said they had detected no such object.

The UN Security Council then passed resolutions prohibiting the North from nuclear and ballistic missile activity.

Foreign officials said there were no indications that a satellite had reached space and that the launch was a cover for Pyongyang to test long-range missile technology.

Pyongyang responded to the UN resolutions by walking out of nuclear disarmament talks and carrying out a nuclear test weeks later.